Gearless differential



April 30, 1957 E. WILDHABER 2790334 GEARLE-SS DIFFERENTIAL Filed Ost. 12, 1953 4 Shets-Sheet s INVENTOR:

E. Wl LDHABER FI ca- |3 April 30, 1957 E. WILDHABER 2,790,334

GEARLESS DIFFERENTIAL.

Filed 0012. 12, 1953 4 Sheets-Shet 4 INVENTOR. ERNEST W! LDHABER FIG.I|

the axis cf the differential, and the view portion being along this axis;

Figs. 2 and 3 are d iagrams explanatory of the preferred Profile curvatures used on the sliding parts and the cam members of this diflerential;

Figs. 4, and 6 arie diagrams illustrative 01: the forces acting 011 a sliding part in the embodiment of the inven tion shown in Fig. l, Fig. 4 showing -the for-ces at zero friction, and Figs. 5 and 6 showing the forces at a coeflicient of friction of 0.15, the load being in the Same direction in both Figs. 5 and 6, but the difierentiation being in opposite direotions;

- Fig. 7 is a diagram Showing the use of a cylindricai pin or roller in place of a sliding part such as shown in Figs. 4 to 6;

Fig. 8 is a diagram illustrating the use of two rollers in a differential constructed ziccording to another embodiment of the present invention;

Fig. 9 is an axial section on a reduced scale of tl1e difierential shown in Fig. 1 and taken at right angles to Fig. l;

Fig. 10 is a fragmentary axial view 0f one of the side members of the housing cf the differential of Fig. 9;

' Fig. 11 is a fragmentary cylindrical section of the two opposite sicle members of the diiferential housing shown in Fig. 9, the cylindrieal section being taken along the line 11-11 of Fig. 9 looking from the outside of the housing inwardly, and being devel-oped or rolled oat into a plane;

Fig. 12 is a part cross-section, part view, similar -to Fig. 1, but cf a somewhat modified embodiment of the invention;

Fig. 13 is a fragmentary axial section of the diflerential shown in Fig. 12 an a reduced scale; and

Fig. 14 is an axial section showing a diiferentiai comstructecl according to the present invention, and showing how my differential iends itself to a novel drive arrangement for an automotive rear axle.

The differentiell of the present invention difie-rs from known gearless differentials in that one of the two cam members is rigid with the rotary difierential housing and receives the whole power transmitted through the differential. The other cam mernber and the enge member receive the divi-ded power. present invention, the two cams contact with the sliding parts at opposite sides of the cam lobes. In known camtype diiferentiais, the contact with the cam lobes is at the same side. Preferably an internal and an external cam member are used, with more lobes on the internal cam member than on the external cam member.

Referring now to the drawings by numerals of reference, and first to the embodiment of th'e invention shown in Figs. 1 to 11 inclusive, 20 (Fig. 9) denotes the axle drive gear which is here formed integral with an internal .cam mernber 21. The power transmitted by the drive gear to the rear axle is divided between an external Cam member 23 and a sage member 24. These have, respectively, rigid, splined connection with the axle shafts 25 and 26. These shafts may be the axle shafts of a pair of driven front wheels or of -a pair of driven rear Wh'eels of an automotive vehicle. While this is so assumed in the illustrated examples, the differential can also act as a torque divider between driven front wheels and driven rear wheels, or between -two pairs of drivenrear wheels, and for other cases.

The cage 24 is provided with a plnrality of equiangularly spaced openings (Fig. 1) which ext'end through the cage radially and which have parallel plane sides 31. In eacl1 of these holes 30 there is"mounted -a part 32 which has sliding radial motion therein. The parts 32 which are sliding blocks, having parallel plane Side surfaces 33, which bear against the side walls 31 of the cage openings 30. 7

4 portions 33 may be rounded off as denoted at 36. At their radially inner ends the sliding parts 30 have sloped portions 37 connected by a connecting portion 33. The connecting portions 38 may be rounded.

The internal cam mernber 21 has a plurality of lobes or teeth 40. These lobes have concave profile portions 41 and are connected by connecting portions 42 which may be rounded. The lobe or cam profiles 41 are adapted to engage the profiles 34 and 36 of the sliding parts 30.

Similarly, the external cam mernber 23 lras lobes 45 fermed by convex main profile portions 46, bottom portions 47, and connecting portions 48 conneoting adjacent profile portions 46. The portions 48 may -be rounded. The cam profiles 46 engage the profiles 37 of the sliding parts 32. 7

The relative motion between the various parts of the ditferential :an best be analyzed and described with refen ence to the enge member. In other words for deseriptive purposes it will first be assumed that the cage member 24 stands still and that the other members and parts rnovc relative thereto.

In the known eam type diflerentials, the two cams movc oppositely with respect to the cage member, and at the sarne rate, if equal torques are to be transmitted to the tw0 driven shafts at zero friction. In the diiferential 0f the present invention the two cams 21 and 23 move in thc same direction with respect to the cage member 24, and the external cam 23 should move exactly twice as fast as the internal cam 21 if equal torques are to be transmitted to the two driven shafts 25 and 26 at zero frietion. During this relative motion of the cams the sliding parts 32 reciprocate in the cage 24. The number cf complete recipnocations of a sliding part 32 back and forth per turn of a cam member 21 or 23 is equal to the nurnber of lobes of the respective cam mernber. As the external cam 23 tnrns twice as fast as the internal cam member 21 in the considered case, th-e number cf lobes of external i cam 23 should be half the number of iobes of the internal In the differential of the A1: its radially outside end eaeh part 32 has sldping cam 21.

At zero friction, the cage member 24 receives no energ5r, as it stands still in the case assumed. The total energy would then be transrnitted from the internal cum member 21 to the external carn member 23. As the latter turns twice as fast as the former, its torque is half as large. In other words, at zero friction, the external carn 23 with half the number of lobes gets half -the torque of the internal cam. 21. The remainder has then to bc trans mitted to the cage member 24. lt gets also one half tl1 total torque. Both the cage member and the external cam, therefore, receive equaltorques, half of the total torque, at zero frietion. This torque distribution is independent of the motion and applies, also, when, as in the case illustrated in -the drawings, the eage member moves. Thus, it is seen that equal torqne is transmitted t0 the two driven members at zero friction, when the number of lobes of the internal and external carns is at the ratio 05 2 to l, as statecl above.

Unequal torques are attainable by altering tl1e num'oer of lobes. Thus, if it is desired that the external cam receive one third of the total torque at zero friction, then its number cf lobes shoul-d be one third of the number of lobes of the internal cam. Actually it should be less than bne third because of ti1e presence -of friction. In all cases, the two cams turn at rates inversely proportional to their number of lobes.

When the-two carns mm imiformly in this proportion eachsliding part 32 moves along its radial guides. The question noW an'sies: does it move at a uniform rate upon uniform rotationof the cams? T he sliding parts of the known art are intended to move at a uniform rate in the region of their middle positions, away fl0tl1 the region 015 reversal.

I have discovered that more favorable cond itions o1? contact can be attained by motion of the slidingparts m a varying rate in the region of and near their middle posit-ions.. This region corresponds to the working PI'OfiIQSj where driving torque is transmitted, to profiles 34 an.d 41and to profiles 37 and 4%.

At and near the middle positions the rate -of travel of a sliding part 32 should increase with increasing distance of the part from the cam axia as will furt her 'be shown.

Fig. 2 shows a preferred form of conta-ct for the sloped outside working profile 34 of a sliding part 32, while Fig. 3 refers to a preferred form of contact at the rofile 37 adjacent the inner end of the sliding part. A mean Position of the =sliding part 32 is shown in full lines. 50 denotes the c-ommon axis of the cam members and o1: the cage member. Mathematically full surface contact between a sliding part and the cam engaged thereby is impossible with radial motion of the sliding part. However we can closely approach it. This is one of the objects of the invention.

In each considered position there will be a point of contact where the direction of the contacting profiles is exactly the same. 51 (Fig. 2) is a point of contact between a profile 34 and a profile 41 in a mean osition of a. sliding pari: 32. lt is kept near the middle of the werking rofile 34. The contact normal 52 at point 51 coutains the curvature center 54 of the profile 34, and the curvature center 55 of the cam rofile 41 at the point of contact 51. 56 denotes a radius drawn through the center 50 in the direction of motion of the sliding pa rt 32. 57 is a line drawn through the center 50 perpendicular to the radius 56.

Normal 52 intersects the line 57 at a point 58 which defines the instantaneous motion. As known, the linear velocity of the sliding part 32 is equal to the peripheral velocity cf the cam 21 at the point 58, that is, at the radius 50-58. 58 is the instantaneous center of relative motion.

The largest useful duration of contact is attained when the point of contact moves toward the end of the sliding part 32 when the latter recedes into the cage 24. In Fig. 2 the Sliding part 32 has receded into the cage in the dotted position of the profiles 34 indicated at 34'. The point of contact should then be al 51 near the outside end of the sliding part 32, since all other portions cf the working profile are out of reach of the cam profiles 41. The internal cam 21, of course, reaches inwardly no further than the cage. In other words, as the profiles of the sliding block 32 move from the full line positions to the positions 34', the point -of contact should move p=6054= urvature radius of sliding part profile to point 60 m=6055=curvature radius of cam profile to point 60 p,=6058=cuwature radius of logarithmic spiral to point 60 Then we have the relationship:

5 E Tii lt should be noted tl1at these curvature radii referto a point 60 011 radius 56, and represent the distances -of the curvature centers from the point 60. The curvature radii to the profile point 51 is readily -obtained fr om p, p and p, by adding the distance 60-51.

The above equations also applies to the externalcanm (Fig.-3). Here the curvature radii at the profilepoint 61 am. obtaincdtrom. he eu-r tur tas jl .il2 3*.91r1h b! subtracting the distance 60:61.. i

In the. tw do p it 9 s; 3v 3. Q fl 1e W9 'ki p s the s di P. I 32, cu amre enter- 54114 moved to positions 5.4, 54", respectively, on a; st raight line 62 parallel to the directiorr f; travel f the sli di -ng part 32. Likewise, curvature center 55 has moved to positions 55', 55", respectively, on a circle 64 concentric with the cam ce1rter 50. At infinitesimal displacements, or alsowith finite displacements in the case cf circular arc profilcs, distance 5455' is equal to the difference of the profile radii, and equal to 54-.-1-55:and to 54"..-55' 54'-55' is the contact normal 52' in the inner position cf the sliding block. It intersects the profile 34 at the point of c-ontact 51' which is located as desired near the outer end of the sliding pari;.- 51" on cont act normal 54"-55" is the point of contact in the Shown outer po= siti'on of the sliding block.

C-ontact normal 52' intersects the line 57 at a point 58', the instantaneous center of relative motion. Tl1is point is displaced toward the turningcenter 50 as com pared with the point 58. Radius 58'50 is smaller than radius 58--50. The instantaneous linear velocity o'f the sliding part 32 is equal to the peripheral velocityof the carn 21 at point 58'. It is therefore smaller than in the mean position.

In the outer position of the sliding p=art 32, the instantaneous center of relative motion is at 58", -at an increased distance from the turning center 50 of the cam 21.; Accordingly, the instantaneous linear velocity o f the s liding part 32 is here larger. On uniform rotati6n -of the cam 21 the sliding part 32 increases its linear velocity with increasing distance from the cam axis 50.

For the contact between the sliding part 32 and the profile of the external cam 23 (Fig. 3), the same motion of the sliding block 32 should be attained. The two positions 34, 34" of the working profiles of the sliding part 32 are at the same distances fr-om the r-nean position 34 as are the two positions 37', 37" (Fig. 2) from mean position 37. Accordingly the eontacts of the sliding part 32 with the external cam 23 should result in the same instantaneous velocity of the sliding part as already determined for the internal cam 21.

As the two cams turn uniE-ormly with respect to the cage member 24 at the inverse ratio of their numbers .of lobes, the instantaneous center 68 (Fig. 3) at the mean position is at a shorter distance 50-'68 from the turning centex 50 than the instantaneous center 58 of Fig. 2

but is also located on line 57. These dis tances ar'e in proportion to the nu-mber of lobes of the respective cams This is to attain the same instantaneous vel0city on the sliding part 32 when in contact with the 'externa'l cam 23 as when in contact with the internal c-am 21. Likewise, the instantaneous centers 68', 68" are at proportionally smaller distances from turning center 50 than instantaneous centers 58, 58", respectively. The whole array of points 50, 68', 68, 68" are a reduced pictureof the array of points 50, 58, 58, 58", the reduction being in the ratio of the nundbers Of lobes .of the respective carns.

Preferably I use circular arcuate '-profiles, at least with the internal cam 21. The working profiles 34, 41 are then circular arcs; and 54, 55 are the centersof these arcs.

By selecting both profile curvatures or both contacting 7 pr0files 34, 41, the relative motion is -determined. lt is also possible' to -start out with a give n -motion and one cf the two contacting profiles, -and then to determine the othe1 mating profile.

In determining the mating-profil6s of the sliding-parts 32 and the external c'am 23, the given p0sitions of-th: instantaneons centers have to be realize'd. One way=t do -this 'is to ass urrie profile 37 -as a circulai-r an: -whosev center is-well beyond point 68 in the middlefpoit ionpancl to determine the -mating -profile of the cam3 from giver'r 'profile- 37 and from -the-given positions of the instantam': ous centers of relative motion. 7 It s l1ould be understood that the above described determination of the mating profiles applies to all cam-type diflerentials, including those where the cage mernber is rigid with the drive gear.

The partial locking action Fig. 4 shows theforces exertedupon the slicling part 32 at its mez'm position, assuming zero friction. The fotces or loads are then exactly perpendicular t the profiles 34 and 37. Thus the driving load applied at point 51 Passes througl1 point 60 and also through point 62. 60-62 represents the driving load, in direction 215 well as in amount. The load reaction of the external cam 23 is applied at point 61; and 6360 represents this load, in direction as well es in amount. Thereaction from the gi1ideways 31 of the cage is perpendicular to the gui leways and passes also through point 60, so that the three forces balance one another. lt is applied at point 64. 62'63 represents this reaction in direction as well as in. amouxit. Loacl determining procednres of this kind are well known in engineering.

The torques exerted on the cage member 24 and on the external cam member 23 at zero friction are proportional to the peripheral components of the fernes passing through point 60. They are proportional to die tance 62--63 and to the distance cf point 63 frorn radius 56.

In the illnstrated example the number of cam lobes im: fourteen and six, respectively, making a diflerence of eight. The torque applied by the internal cam 21, and the torque recei ved by the external cam 23 are in the roportion of the nurnbers of lobes, that is, of rourteen to six at zero friction. The torques exerted on the driven members at zero friction are in the roportion of six to eight.

Figs. S 'and 6 are similar to Fig. 4 but show the forces as they actually exist with friction. A friction coefllcient of 0.15 has been assumed in Figs. 5 anal 6. Fig. 5 refers to the case where the sliding part 32 is moving inwardlythat is, toward center 50 under the applied load. Fig. 6 refers to the case where the sliding part 32 moves outwardly under the applied load.

The foree applied'at point 51 in Fig. 5 is no langer perpendicular to the working rofile 34 of the sliding part, but is slanted as sh'own.v It is inclined to the profile normal at point 51 by the friction angle, the angle wl1ose trigonometrical tangent equals the friction coeflicient. The load reaction of' the external cam 23 is still applied at Point 61, bnt is also slanted to the profile normal as shown. The two forces intersect at 60 (Fig. 5). The reaction from the guideways of the cage is also slanted on account of the motion of sliding part 32. lt asses through point 60' and extends along the dotted line 69', being applied at the point 64'.

60'65 repr'esents the driving load, in direction as well as in amount; 66-60 likewise represents the load reactio'n of the exteri1al cam 23; and 65-66 represents the load reaction of the ca1ge 24. Point 66 happens to fall on the profile 37; but this is a coincidence.

The driving torque equals the procluct of radius 50-60 multiplied by-the component of the force 6065which is' perpendicularlothisjradius. Inasmnch' as all three forces passthrongh point 60', their torques are proportional to the force components perpendicular to radius 50-60'. 011 the clriven members these components and the torques are found by scaling to be in the proportion of about four to one. 'I'he cage member receives, therefore about four times as mach torque es the external cam memberat the assumed direction of differerxtiation. The results arereversed in Fig. 6 whi ch refers to the outw ard motion of the sliding part 32 under load. The

driving load is still applied at point 51, but is now slante in the opposite. direction to the profile normal. This is also true of the load reaction of the external cam applied at point 61. The two forces intersect at a point 60". As this point is beyond the guide ways 33 of the sliding part, it takes reactions from both sides 0f the guide ways 1:0 maintaln load balance. This increases the friction in the guide ways so that the load taken up by the guide ways has an increased slant.

6 "-70, 71-60", and 70-71 represent the driving load, the load reaction of the external cam, and the load reaction of the cage member, in direction as well as in amount. These three fernes Pass through point 60", and their torques are proportional to the force components perpendiculzu to radius 50-60". Scaling shows that the torques exerted on the driven rnembers at differentiation in the assumed opposite direction are in the proportion of approxirnately four to one. Here the external cam member 23 receives the larger torque, a torque about four times the torque received by the cage memher 24.

In other words, driving conditions of the two driven mernbers 23, 24 are balanced 011 the whole. One does just about as much overall driving as the other. This balanced condition exists at lobe numbers of fourteen and six, where the number of lobes of the external cam rnember is less than half the number cf lobes of the internal cam member. More broadly, when p denotes the averaged torque desired on the external cam member 23 in proportion to the total t0rque applied to the internal cam member 21, then the number of lobes 45 of the external cam 23, in proportion to the nnrnoer cf lobes 40 of the internal cam 21, should be somewhat less than p. In this way, the desirecl average torque roportion cf p to be transmitted to the external cam membercan be realized. The cage member then receives the remainder of the driving torque, that is, a torque roportion of (lp).

In Figs. 4, 5 and 6, the driving conditions have been illustrated for driving contact in one direction. For driving contact in the opposite direction symmetrical conditions prevail because the profiles themselves are symmetrical with respect to a central plane extending in the direction of motion of the sliding arts.

Fig. 7 illustrates the condition where a pin or roller 74 is substituted for the sliding part 32. This pin or roller rolls reciproca'ringly in guideways 33 of cage 24. With zero friction the driving torque passes through point 60 corresponding to point 60 of Fig. 4.

Fig. 8 shows how the ower may be transrnitted from an internal cam 75 to an external cam 76 through a plurality cf rollers 77, while also transmitting power to the sage member 78. Hera the cam members und the cage 'rnember are all coaxial and centered at 50.

The general design In the embodiment of the invention shown in Fig. 9, the two side mernbers 80 and 81 of the differential housing are rigidly secured to the drive gear 20 by rneans ol rivets 82. This is a tapered drlve gear such as is commonly used on passenger cars and many trucks. The rivets 82 form a very simple and mgged connection between the drive gear und the differential housing, and may be used in quantity production. Since the internal cam 21 is formed integral with the drive gear, the power flow does not have to pass throug'n any connections. The riv ets do not have to transmit torque, and are not stressed in shear. In the rare cases where failure occurs in the drive gear or the dilferential, the whole unit will have to be replaced; but in quantity production this is hardly more expansive than trying to replace an individual broken part.

The side members 80, 81 and driye gear 20 together 9 form the rotary diflerential housing. -It is .mounted in two anti-friction hearings 83 heldby the side members 80, 81.

A partial end view of sirle mernber 81 is shown in Fig. and a partial peripheral section of the two side members is shown in Fig. 11. Bach side rnember comprises a ring-shaped fiange 84 connectedwith the body 'portion 85 of the side mernber by arms or spokes 86. Op'eningS or spaces 87 are provided between the zsp'okes to permit fiow of ldbricant between the-.outside "anti the'inside of the rotary difierential housing. T0 help such liew, 1 may shape 'the arrns 86 as indicated in Fig. 11, inwh-ich the arrow 87 denotes the direction of forward mot-ion. The forward sides 88 of the -spokes .are sloped as -indicated so that the turning motion 101 the rotar-y differential housing tends to draw in lubricanten one:side-and out 011 the other side. In otl1er words, the arms 86 act li-ke partial tscrews er propellers. The difierential.and.itszhousing, of course, are enclosed in the axle housi-rig itself (=not shown) which may 'be of conventional structure.

The openings 30, in which the :blocks 132 slidesare of rectangular shape. preferably with rounded corners. They are closed at the 00th ends axi'ally of the sage, being closed at one end by the rnain flange -portion 91 of'the cage and at their -opposite ends by the integral parallel flange portion 90. This closed construction adds to the strength -of the cage. The holes 30 can be finished by broaching. Likewise the internal cam lobes 40 can be broached, as the cam 21 is open at both ends. The external cam lobes 45 can also be broached, 0r can be produced by hobbing, milling-or pianing.

The embodiment -0f Fig. 12 dilfers from that of Fig. 1 in {hat the sliding parts 92 are narrower and longer than the parts 32. The parts 92 have a length at least twice their width. 'Hence, whereas the mean normals to the outer and immer profiles in the caseof the embodiment shown in Fig. l intersect in a common point 60, Ithemean normals to the outer working profiles in the case 0f the embodiment cf Fig. 12 interseo't at a point disposed radial'ly outside the intersection point lof the mean normals cf the inner working profiles. This is because in the embodirnent of Fig. 12 the sliding parts 92 have greziter length radially than the shding p.arts 320f Fig. 1. 0therwise it is sirnilar to the embodiment cf Figs. -l to 9 as regards operation. lt cornprises an internal camrnernber 93 formecl integral With the drive.;gear 20 (Fig. 13) which tr'ansmits the whole pt wer pasSing thnough the diflerential, a cage member 94 splined 10 anraxle :shaft 95, anti movably holding parts 92, und an external cam member 96 splined to an axle shaft 97. The cage mernber 94 anal the external cam member 96 reueive the divided power as in the previously describedembodiment :of this invention. Tl1e carn mernbers and cagememlaer are all coaxial.

Tne openings in the sage men1b.er, Which guide'the sliding parts 92 for radial motion, are shown here in the'form of slots. They are open .at one end, at the 1right band end in Fig. 13. If desired, such slots could also be used in the first described embodiment, and viceversa.

Two side members 98 anti 99 cf ditferent diameters respectively, are rigidly secured to the drive gear20 and internal carn mernber by screw b0lts 100 that thread into the side member 99. They nass Ihrough:lroles 102 pro vided in the drive gear 20. These Lholes areinclined to the axis 193 of the drive gear and lie 'on aconicalsurface. Through this provision itis'pdssibhtotuse Ja differential of oomparatively large dimeter. The zrootrsurfaoe ofthe cam lobes cf the interna.l cammayxhave adiameter as large as indicated by the flotted line 104. It may even reach into the screw bolts, as shown, by aligning the scr.ewbolts with the lobes 1of 1the internal carn, and -using a number of screw bolts containedin the nurnber of Lobes. Thus 011 a.oa.rn with fourteenllobes I mayuse sevenzscrew bolts.

faces 105 and are centered oncorresponding=cylindrical surfacesof the drive gear. They alsocontain plane surfaces 107 of ring shape which match and seat againstcor-v responding plane surfaces on the drive gear. The-side members 98 and 99 -carry bearings 108, 109 vfor moun ing the rotarydifferential thousing composed of the side members and the drive gear.

It has -already been shown that the numberof Lobes of the external cam mernber should be somewhat lass -than half the number of lobesof the internal:carn member to transrnit the sann-e averaged torques to the two driven shafts. Thus, in the illustrated examples, these numbers are six and fourteen. A still more important eifect results fromsuch a pro vision. Various sliding partsxhave d'ifierent phases. If the lobe numbers weresixand twelve there woiuld ne ne phase dilferenee. 1t would fthenbe necessary to pro-Vide a jplurali ty of -r-ows of slidingparts. This would complicate the differential -and make.it-more costly, alsowider.

The differen't phases are readily seen in Figs. l .and I2. In each relative position of the cams there are som'e sliding parts in a positi'on to transmittorque. Preferably I keep the lobe nurnbers even .numbers so that diametrically opposite parts are in the Same phase. Equal forces are then applied at two diametrically opposite points, giving puremoments erlerques.

The maximum number of ssliding .parts (32 01' 92) whi'ch can be used in my cam type differential can be shown to be equal to the dilierence 0f the number of carn lobes on the two carns.

The difierential of Fig. 13 has a comparatively large diameter so that its l0ads are moderate. It can be kept narrow and eompact. Its cost is 10W. This applies also to the other emb-odiments. The sliding parts can be cut 011 from bar stock finished for instance by cold drawing, 01 cold rolling. N0 gear cntting operaticx-ns are required on them.

The narrow width cf this differential opens upneW design possibilities. Fig. 14 illustrates such .a new design embodiment as applied .to the 'rear axle of a passenger car or truck. In this emb-odiment the final drive is a hyp:oid drive eonsisting of a;hypoid pinion 119 and a hy-' poid drive gear 120. The latter is formed integral Wi'th the internal carn rnember 93 ofa gearless di'fferential 'as described with reference to Fig. 13. A sage member 94' anal an extern'al catn m'ember 96' Ireceive the divided p ower through the sliding parts 92. a'ndare splined to the axle shafts 95 .and197. 011 passenger cars arid many trucks, the nonventional mounting of the hypoid pinions'is the-Over-hung mounting, that is, ithe pinion is moun'ted on two bearings bot'h disposed back of the pinion. Tnis requires a carrie1" which stands out frorn the axle 011 the driving side.

A more compact axle is attainable with the present invention, for1the pinion 119 may be-rnoun'ted, as shown,

' between two bearings 122, 123, disposed 011 opposite noller bearing. The other bearing 125 is adapted to take axial thrust in both directions, as well as radial loatls.

The gear 120 can*be adjusted along its axis by mereljr adjusting bearing 125. In such adjustment, thecylindrical rollers cf bearing 126 slide latlera'lly an tneir outer races.

Witl1 the described arrangement, the 'pinion sn-aft 127 has to by-pass onlY theiaxle shaft97, anti no part'of the rotary differential housin'g. Thesh-aft offsetmeds 'ofily to be slightly larger than 7the surn' of"the "shaft raclii, and The =side members 98 311d99'0011113111 mzyilindrical surnb excessive offsetis neecled. The pro'jectin'gpi'xilon shaf:

' 11 inzty be -formed integral with the hypr id pinion 119 as shown Q1, if desired, the shaftancl pinion may be made ii1-iwo parts which ar e then rigidly secured together.

In the described embodirnents I have shown cam lobes with comparatively large slope to the peripheral direction, to attain moderate loads. However, other slopes can also be found. Smaller slopes result in increased loads at the cams and increased friction,that is, increased braking of the relative motion at ditferentiation. Completely locking diiferentials may be achieved, if desired, by sufliciently reducing the cam slopes. In such difierentials the drive around a curve is on the inner wheel only, the outer wheel over-running the inner wheel.

With the present invention, the internal cam member cam be made larger than heretofore possible be iause it is now rigid with the outermost part of the diifereiral', that is, rigid with the rotary differential housing. Heretofore, the internal cam member had to be inside the rotary differential housing, and movable relative to the housing With the diiferential of the present invention, moreover, the internal cam member ca1i be made integral with the drive gear and can be open at both encls so that it ean be made with more productive processes than has heretofore been possible in making such members, as, for instance, broaching. 'I'he present differential also lencls itself well to the use cf a single row cf sliding parts, and does not require multiple rows. Furthermore, the rotary differential housing cam be made up of the drive gear with its integral internal cam member and of two side members rigidly secured to the drive gear, whereby the connection between each side member and the drive gear transrnits 110 torque and is free of shear stress. Last, but not least, the differential of the present invention cam be produced at low cost.

While the invention has been described in connection with several different embodiments thereof, it will be un derstood that it is capable cf further modification, and this application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come Within known or custornary practice in the art to which the invention pertains, and as fall within the scope of the invention or the limits of the appended claims.

Having thus descn'bed rny invention, what I claim is:

1. A gearless difierential comprising two coaxial cam members, a cage member coaxial with said cam members, and a plurality of movable parts held by said cage memher and each engaging both of said cam members, one of said cam members being the driver and transmitting the whole power passing through the differential, and the other two coaxial members being each connected to a shaft to transmit thereto part of the power.

2. A gearless differential comprising an internal cam member and an external cam member coaxial therewith, a sage member coaxial With said cam members, a plurality of parts movably held by said sage member and each erigaging both of said cam members, and a drivegear, said internal cam member being rigid with said drive gear and transmitting from said drive gear the whole power passing through the differential, the other two coaxial members beirig each connected Willi a shaft to transmit thereto part of the power. v 7

3. A gearless difierential comprising an intemal cam member and an-exte1n2il cam member coaxial therewith, a cage member coaxial with said cam members, a plurlity cf par ts movably held by said cage member in radial openings thereof, each of said parts engaging at its opposite ends, respectively, with both cf said cam members, and a drive gear, said internal cam member being rigid with said drive gea r and transmitting from said drive gear the whole power passing through the difierential, the other two coaxial members being eacl1 connected with a shaft to transmit thereto part cf the power.

4. A gearless difierential comprising two cuaxial cam members, one of said cam members being larger than the other, a drive gear, the larger cam member being integral with said drive gear and transrnitting frorn said drive gear the whole power passing through the differential, two side members rigidly secured to said larger carn member at opposite sides thereof, a bearing carried by each cf said side members for rotatably mounting the differential, a cage member coaxial with said cam members and mounted between said cam members, a plurality 0f parts movably held by said sage member and each engag ing both of said cam members, said cage member and the smaller cam member being each connected with a sh aft to transmit power to said shafts.

5. A gearless diiferential comprising two coaxial cam members, each having a plurality of lobes, one of said cam members being larger than the other and havin'g more lobes, a drive gear, said larger cam member being formed integral with said drive gear and transmitting the whole power passing through said differential, said larger cam member having a plurality of angularly-spaced holes therethrough which are inclined to the axis of said larger cam member and equally spaced about said axis, two side members of uneciual diarneters, means extending throngh said holes for securing said side members to said larger cam member, a bearing carried by each of said side members for rotatably mounting the diiferential, a cage member coaxial with said cam members, and a plurality 0f parts movably held by said cage member, each of said parts engaging both of said cam members, and both said sage member and thesmaller cam member being each connected to a shaft to transmit power to said shafts.

6. An automotive diiferentiai comprising a tapered drive gear, an internal member formed integral With said drivc gear and transrnitting the whole power passing through said differential, said internal member having a plurality cf holes inclined to the axis of said drive gear and equally spaced about said axis, two side members whose maximum outside diameters are unequal, means extending through said holes for rigidly securing said side members to said internal member, a bearing carried by each cf said side members for rotatably mounting the difierential, two shafts mounted coaxially with said drive gear, and means connected with said internal member for dividing the power transmitted through said internal member between said two shafts, whereby said two shafts may turn relatively to one another.

7. A gearless difierential comprising two coaxial multilobed cam members, a cage member coaxial with said cam members, and a plurality of arts movable in said sage member and each engaging both cf said cam members, a pair of driven elements, one of said cam members being the driver and transmitting the whole power passing through the differential, the other cam member and said cage member each being connected to one cf said driven elements and eachtransmitting part of the power, and said one cam member having more than twice as many lobes as said dther cam member.

8. A gearle'ss diiferential comprising two coaxial multilobed cam members, a cage member coaxial with said cam members, and a plurality of parts rnovable in said cage member and each engaging both of said cam members, a paii of driven elements, one of said cam members beim; the driver and transmitting the whole power passing through the difierential, the other cam member and said cage member each being connected to oneof said driven elements and each transmitting part of the power, said one cain member haflng more lobes than the other cam .rnember, and the number of said movable parts being -1 hrough the rdifierential the other cam .memberrand said 2;:age member each being connected toone of said driv.cn elements and each transmitting part of the power, said one cam member hangmore lobes than the other cam member, the nurnber of lobes on each cam member being even, and the number cf said movable parts being eqnal to the diiference in nnmber f the lobes of the two cam members.

10. A gearless differential comprising an internal cam member, an external cam member, and a cage member, said members being coaxial, and a plurality of sliding parts radially movable in said cage member, each of said sliding parts engaging both cam members, the werking profile of a cam member and the mating worklng rofile of a sliding part having opposite curvature, one of said working profiles being concave and the other being convex, the curvature centers of said working profiles at a mean point of contact lying at cpposita sides of a radius perpendicular to the direction of radial movement of each sliding part, said radius passing through the axis of said mernbers.

11. A gearless difierential comprising an internal cam member, an external cam member, a cage member, said members being coaxial, a plurality of sliding parts radially movable in said cage member andeach engaging both cam members, each of said cam members having a plurality of lobes whose total profiles are made up of working profiles adapted to transmit torque and of connecting portions, the working profiles of the internal cam mernber and the mating working profiles of the sliding parts being circular arcs, and the centers of said arcs at a mean point of contact lying at opposite sides cf a radius drawn through the axis of said mernbers perpbndicular to the direction of travel of each sliding part.

12. A gearless differential comprising a multilobed internal cam member, a multilobed external cam member, a cage member, said members being coaxial, a plurality of sliding parts mounted in said cage member for movement radially of the common axis of said members, each of said sliding parts having a pair of cppositely inclined working profiles at both its outer and its innsr ends which engage said two cam mernbers, the pair of working profiles at the outer end of each sliding part being separated by a portion extending in th-s peripheral direction of said cam mernbers, and the working profiles of the lobes of said external member being separated at their roots by peripherally-extending dwell portions.

13. A gearless differential comprising a multilobed internal cam member disposed to receive the whole driving power, a multilobed external cam member, a cage member, all said members being coaxial, said extsrnal member and said cage member being connectedrespectively, with coaxial driven elements, and a plurality of sliding arts mounted in said cage member for movement radially of the common axis of said members, each of said sliding parts having a pair of oppositely sloped working profiles at its outer end and at its immer end, which engage the two cam mernbers, the mean normals to the outer working profiles interseoting each other at the same point at which the rnean normals of the inner working profiles intersect.

14. A gearless difierential comprising a multilobed internal cam member disposed to receive the whole driving power, a multilo'oed external cam member, a cage member, all said members being coaxial, said ex ternal member and said cage member being connected, respectively, with coaxial driven elements, and a plurality of radial guide openings provided in said cage mernber, the number of said openings being equal to the difference in number of the lobes provided on said cam members, and means movable in said openings and engaging both cam members.

15. A gearless diflerential comprising a multilobed internal cam member disposed to receive the Wl'lole driving powe1ta multilbedfliteifnil cam member, a cage member, said three mernb.ers b.eing coaxial said external cam memner and s:l cage me mber.bdin g sonnected, respectively, W'ifh coax'ildiiven elements; a plur2il'ity .of sliding parts mor'ite'in said 1cage member for movernent xal'ially of Ehe cor'nmon axis of said menibens, eacn of said sliding part's'l1aVinga pa'ir of oppositly indlined working profiles at its outer and its inner ends which engage the two cam members, the ends of each sliding part being so spaced from each other that the mean normals of the outer working profiles intersect at a point disposed radially outward of the poi nt of intersection of the mean normals of the inner working profiles.

16. A gearless diflerential compris ing an internal cam mernber, an external cam member, a cage memcer, all said mernbers being coaxial, two driven elements, one of said members being the driver, and the two other members being each connected with a driven element, a plurality of parts slidable in said cage member radially of the comrnon axis of said members and engaging said cam members, each cf said cam members having a plurality of lobes whose total profiles are n1ade up cf werking profiles adapted to transmit torque and of connecting portions, said sliding parts having working profiles adapted to mate with workdng profiles of said cam members, a working profile of the internal cam member and the mating working profile of a sliding part being concave and convex, respectively, a working profile of the external cam member and the mating working pro file of the sliding part being convex and concave, respectively, the average curvature of each pair of mating, contacting working profiles beim; approximately equal to the curvature of an arc contacting them and centered on a radius drawn through said comrnon axis at right angles to the direction of motion of the sliding part, the curvatures of the contacting profiles cf each pair of mating profiles diflering so that uniform rotation cf the cam members causes a sliding part to rnove in a stationary cage member at a rate that increases with increasing distance of said part frorn the axis of the members.

17. A gearless diflerential comprising a multilobed irrternal cam mernber rigid with a driving element, a multilobed external cam member with fewer lobes than said internal cam mernber, a cage member, said man bers being coaxial, two driven elements, said externai cam member and said cage member being each sonnected with one of said driven elements, a piurality of sliding parts mounted in said cage member for movement radially of the corinnon axis of said memners each of said sliding parts having a pair of opposite workin g profiles at its outer and inner ende; respsctively, which engage the two cam members, the unter working profiles comprising two convex circular arcs that are inclined to each other and that are jo ined by a connecing portion, the inner working profiles comprising two concave circular arcs that are inclined to each o ther anal that are joined by a convex connecting portion, the lob'cs 0f said cam rnembers also being compcsed of working profiles and connecting portions, said working profiles carrying the main load and occupying more radial d-apth than said connecting portions, each wofking profile of said internal cam member being a single 'concave circular arc, and each working profile of said external cammenr bei being a single convex circular am.

Referencas Cited in the file of this patent UNITED STATES PATENTS 1,336950 Ford Apr. 13, 1920 1,770,314 Lancia July 8, 1930 1,776677 Brewer Sept; 23, 1930 (Other references on foilowing page) 15 UNITED STATES PATENTS Robbins Dec. 15, 1931 Robbins May 10, 1932 Spicacci Jan. 3, 1939 Wemp Apr. 4, 1944 Robbins Feb. 6, 1945 Schmidt Dec. 18, 1945 Robbins July 17, 1951 Patch Oct. 13, 1953 Viebrock Jan. 25, 1955 FOREIGN PATENTS Great Britain Nov. 3, 1937 

